Analytical strategies for the detection of counterfeit erectile dysfunction drugs.

peer reviewedAmong all classes of drugs, the type 5 phosphodiesterase inhibitors (PDE5-i) (sildenafil, vardenafil and tadalafil) are the most counterfeited and copied in industrialized countries. This is why it is very important for regulatory agencies to have a panel of analytical methods to analyse these drugs and to be able to detect counterfeit or substandard medicines. During this chapter, several analytical techniques will be described and discussed. Among spectroscopic techniques, Raman, NIR, FT-IR and chemical imaging techniques will be envisaged. Their ability to detect counterfeits and predict if a new sample is genuine or not will be presented. Other techniques such as XRay powder diffraction and NMR spectroscopies will be briefly presented. Chromatographic impurity fingerprints will be considered and described for the analysis of suspect samples of Cialis® and Viagra®. Once again, the possibility to predict the authenticity of a new sample by the mean of this technique is envisaged. Finally, a MS-compatible UHPLC-UV method for the analysis of the three authorised PDE5-i and some of their analogues will be shortly described. This technique has been validated using spiked placebo samples in a vegetal matrix representing a suspect sample with a complex matrix. As a conclusion, a generic strategy for the detection and quality evaluation of counterfeit drugs will be presented